Chris Crompton, Peng Jian, Daniel Apt, Mark Grey

Keywords： Low Impact Development; Orange County; Implementation; Assessment

Abstract：

This paper discusses Orange County’s transition from a conventional urban development approach that resulted in significant damages to natural stream morphology, habitat, and water quality to a more balanced approach that attempts to balance predevelopment and post-development hydrology to protect these resources. It then summarizes the framework and innovative approaches being undertaken to implement and assess the Low Impact Development (LID) in Orange County. Participating in the regional study to understand the effectiveness of LID, Orange County has developed guidance documents and created a systematic framework to assess the LID performance. These are aimed to standardize the LID approaches and develop alternative compliance program through water quality credit trading in the LID-restricted areas. Through two case studies, Glassell Campus Stormwater LID Retrofit Project and Legacy Campus Water Quality Credit Trading Program, we find out key factors to the success of LID implementation include: the site survey, modeling, and monitoring prior to the project design; the post-project standard monitoring and data sharing; and the flexible water quality credit trading system. China can potentially learn from Orange County’s experiences for its implementation and assessment of LID.

Funds：

• [1] Prince George’s County. Low Impact Development Design Strategies an Integrated Design Approach[R]. 1999.
  [2] County of Orange. Technical Guidance Document (TGD) for the Preparation of Conceptual/Preliminary and/or Project Water Quality Management Plans (WQMPs)[R]. 2011.
  [3] County of Orange. Model Water Quality Management Plan[R]. 2011.
  [4] County of Orange. Hydromodification Guidance[R]. 2011 & 2013.
  [5] Southern California Stormwater Monitoring Coalition. California LID Evaluation and Analysis Network (SMC CLEAN) Standard LID Project Data-Information List[R]. 2016.
  [6] Southern California Stormwater Monitoring Coalition. California LID Evaluation and Analysis Network (SMC CLEAN) Standard LID Monitoring Protocol[R]. 2017.
  [7] Southern California Stormwater Monitoring Coalition. Low Impact Development Manual for Southern California[R]. 2010.
  [8] OC Public Works. Glassell Campus LID[DB/OL]. 2017. https://www.youtube.com/watch?v=1dEUJsMiFJo.
  [9] County of San Diego. Water Quality Equivalency Document[R]. 2015.